Britain brandished a diplomatic olive branch today as it tried to restart global climate change negotiations with an initiative to heal the rift between rich and poor countries following the failure of the Copenhagen summit.

Climate secretary Ed Miliband conceded considerable ground, offering to sign a new Kyoto treaty as developing countries' demand, but while also requiring that those nations enshrine their commitments to tackling global warming in international law.

The initiative could lead to two separate global treaties on climate change. It also offers a challenge to China, India and other major developing countries, who have been unwilling to commit legally to acting on climate change because the Kyoto agreement specifically exempts them.

"We are asking that developing countries internationalise in a legally binding agreement the actions they take domestically," said the government action plan, published today in advance of formal UN negotiations that reopen next week in Bonn.

"We would not envisage developing countries being subject to any punitive compliance measures," it added.

The move is the strongest signal yet that rich countries' attempts to sideline or even abandon the Kyoto treaty have failed and that the negotiations will continue within the 192-nation UN climate body and not in smaller groups of countries as the US and other nations had wanted.

"We hope by doing this we can take away the myth that developed countries were trying to destroy Kyoto," said Miliband.

"We are determined to unblock the negotiations. We are willing to offer a second agreement under Kyoto, provided there is a separate legal treaty covering all other countries."

The move was immediately welcomed by Bharrat Jagdeo, president of Guyana. But he warned that developing countries would not accept an agreement if rich countries – who have emitted by far the most carbon pollution – did not commit to further deep cuts in emissions.

Referring to the US, he said: "There are countries who stick out and clearly need to do more work. If the largest [developed] country emitter falls so far below the minimum, it makes it far harder for other countries, and you lose the element of justice and fairness."

The diplomatic moves came as Gordon Brown met billionaire financier George Soros; Obama's economic adviser Larry Summers; economist Lord Nicholas Stern and other finance ministers to find ways to raise $30bn (£20bn) a year immediately and $100bn a year by 2020 to enable developing countries to adapt to climate change.

The high-level advisory group on climate change financing, convened by UN general secretary Ban Ki-moon and chaired by Brown and Ethiopian prime minister Meles Zenawi, will consider at least six ways of raising up to $1tn dollars for climate change adaptation. These include:

The group of 19 financial leaders have been asked by Ban to report back by November, when UN climate talks take place in Cancun, Mexico.

Environment and development groups welcomed the British initiative. Andy Atkins, Friends of the Earth's executive director, said: "It's positive that the government has restated its commitment to the Kyoto protocol, which enshrines the responsibility of rich countries, as the biggest historical polluters, to slash their emissions first and fastest."

Joanne Green, head of policy at development agency Cafod, said: "This shows that Gordon Brown is listening to the concerns of developing countries. This is a first stride in rebuilding the trust desperately needed between developing and developed countries."

And Melanie Ward, Christian Aid's UK political adviser, said: "The positive language needs to be matched by the necessary political choices.

"These include using international finance to support clean development in poor countries, rather than more dirty coal power stations, and demanding much deeper cuts in EU emissions levels."